For many years insoles have been produced to simulate the bottom contour of the human foot in an effort to provide the wearer with a greater degree of comfort, supporting the arch and reducing the shock of impact while walking, running or jumping.
The methods and materials employed were laminated insole boards which were compression molded as in conventional shoemaking, cast and cured natural latex foams, injection molded or open mold cast polyurethane foams, elastiomeric polymers, compression molded crosslinked polyethylene foams, cut and skived foam components from sheet stock, leather and various combinations thereof.
Such insoles all have one basic concept in common, they are all made over, or in, molds which for practical and economical reasons hav a limited number of sizes, often as few as four, seldom more than about eight to twelve. It is therefore understandable that a limited number of molds will necessitate compromise in design and detail for fear of creating pressure points and discomfort to the individual's feet.
It is however a well known fact that the shape and size of the human foot shows an infinite number of variables, and that not even the right and left foot of an individual are exactly the same.